We are examining the chemical composition of bone from the knee joints of cynomolgus monkeys. A comparison is being made between intact monkeys (Sham-ovariectomized) and ovariectomized monkeys. An extensive clinical database is available for all animals, including bone densitometry, CT scan, and bone biomarker data. The ovariectomized monkeys show a marked reduction in bone mass, consistent with osteoporosis. Although it is clear that bone mass is significantly reduced in osteoporosis, and the subchondral bone is thickened in osteoarthritis, it is unclear whether bone that is formed differs from normal bone. This issue is extremely important because the chemical composition of bone not only affects its strength and flexibility, but also influences the process of remodeling because it affects hydroxyapatite crystal size, density, and solubility. Infrared microspectroscopy is being used to compare variations in bone Hmorphology with bone compositional features such as protein/mineral Hratios, mineral crystallinity, protein composition, and mineral Hcomposition. Comparisons are made between (1) normal vs. osteoporotic Hand osteoarthritic bone, (2) cortical vs. cancellous bone, and (3) Hold bone vs. new bone. Cortical bone will be mapped with the osteon Hmethod and cancellous bone, including trabecular bone, will be mapped Husing the transverse method. The osteon method involves collection of Hline scans from the four orthogonal directions of an osteon. The Htransverse method involves collection of line scans that transverse Hregions of cancellous bone. For subchondral bone, maps begin at the Hmarrow space and end in the cartilage.